Attachment for a buttonhole stitching machine



Feb. 24, 1959 A. HOLLAND 2,874,660

ATTACHMENT FOR A BUTTONHOLE STITCHING MACHINE Filed May 3, 1957 2 Sheets-Sheet 1 I"\gi INVENTOR.

ALBERT HOLLAND v BY ATTQRNEYS Feb. 24, 1959 A. HOLLAND ATTACHMENT FOR A BUTTONHOLE STITCHING MACHINE Filed May 3, 1957 2 Sheets-Sheet 2 R. m N w m ALBERT HOLLAND United States Patent F ATTACHMENT FOR A BU'ITONHOLE STITCHING MACHINE Albert Holland, Collierville, Tenn.

Application May 3, 1957, Serial No. 656,885

3 Claims. (Cl. 112-68) The present invention relates generally to an attachment for a buttonhole stitching machine and in particular to an attachment for restraining operation of the buttonhole threading mechanism upon breakage of the buttonhole sewing thread.v

An object of the present invention is to provide an attachment for a button hole stitching machine which, upon release of tension in the sewing thread for ,any reason, automatically prevents the operation of the cutter knife employed to sever the threads of the work piece fabric between the completed buttonhole stitches.

Another object of the present invention is to provide an attachment for a buttonhole stitching machine which is sensitive in operation, one which restrains the operation of the cutter knife upon breakage of either the upper or the lower thread, one which is simple in construction and readily and easily attached to stitching machines having latch lever mechanism associated with a lost connection mechanism, one which is sturdy in construction and of long life characteristics, and one which is highly effective in action. I

These and other objects and advantages of the present invention will be fully apparent from the following description when taken-in connection with the annexed drawings, in which:

Figure 1 is a side elevational view of a portion of a button hole stitching machine with the attachment of the present invention secured thereto;

Figure 2 is a sectional view taken on the line 2-2 of Figure-l and drawn on an enlarged scale;

Figure 3 is an exploded view of the components of the attachmentvaccording to the present invention, with one of the components of the stitching machine;

Figure 4 is a fragmentary elevational view of the attachment in a position disengaged from the latch lever of the stitching machine; and

Figure 5 is a view similar to Figure 4 showing the latch lever in engaged position.

The attachment according to the present invention is intended for use with a buttonhole stitching machine, shown fragmentarily in Figure 1 and designated generally by the reference numeral 10, such machine including an arm 12, a head 14 carried in the free end of the arm 12 and a needle bar 16 vertically mounted within the head 14 for reciprocatory movement. The sewing thread is designated by the reference numeral 18 and is shown, in Figure 1, entering the upper open end of a thread leader post 20 which rises from the arm 12. The thread 18 extends from a hole in the side of the post 20 to a tensioner 22 and thence through a thread guide 24 to a second tensioner 26, having the usual number of tension applying disks therein, and thence to a spring take-up 28. 'From the take-up 28 the thread 18 rises vertically to a thread take-up arm 30 and thence enters a slot 32 in the head 14 and descends to the needle 34 in the conventional manner.

The buttonhole stitching machine also includes a knife 36 which is dependingly carried by a knife holder 38 attached to the lower end of a knife bar 40 which is reciprocally mounted within the head 14 for upward and downward movement of the knife 36 into and out of .a fabric work piece to thereby sever the fabric of-the work piece between the buttonhole stitches after the of in the frame or arm 12 of the machine. A cam roller 48, driven by the machine driving mechanism, imparts rocking action to the driving lever 46 when the machine is in operation.

The end'of the power operated lever 46 remote from the cam roller 48 is provided with another hinge screw 50 for the pivotal connection of an upwardly extending latch lever support arm 52. The upper end of the latch lever support arm 52 is provided with a closed slot 54 through which extends a horizontally projecting stud 56 carried by the adjacent end of the knife driving lever 42. A latch lever 58 is pivotally mounted intermediate its ends upon the mid portion of the arm 52 for rocking movement about a horizontal axis and is provided on its upper end with a shoulder 60, shown most clearly in Figure 3, engageable under the projecting portion of the stud 56 for positively locking the lever 42 to the lever 46. The connection of the stud 56 in the slot 54 is a lost motion connection which is normally in unlocked position.

The latch lever 58 is urged by a spring 62 into the position in which the shoulder 60 underlies the stud 56 to interlock the levers 42 and 46 together so as to transmit the upward movement of the end of the lever 58 carrying the hinge screw 50 to the lever 42 to effect the downward movement of the connected knife bar 40 and to thereby efiect the downward movement of the cutter or knife 36. The actuation of the latch lever 58 is the reference numeral 64 in Figure l. The trip mechanism is cyclically operated in response to the completion of buttonhole stitches formed in the fabric by the buttonhole stitching mechanism including the needle 34.

The attachment according to the present invention comprises a vertically disposed supporting plate 66 easily and readily attached to the frame or arm 12 of. the machine, there being a hole 68 (Figure 3) receiving the hinge screw 44 for attaching the plate 66 on the arm 12. A brace member 70 extends from the mid point of the plate 66 adjacent the upper edge of the latter to a removable set screw 72 on the arm 12 and serves to maintain the plate 66 in the vertical position.

A first horizontally disposed lever 74 is connected adjacent its mid point to the plate 66 for movement upwardly and downwardly about a first axis which is arranged transversely of the plate 66. Means, embodying an L-shaped bracket 76, is carried by the plate 66 and is engageable with the lever 74 for limiting the downward movement of the one end portion 78 of the lever on the end of the lever 74 remote from the portion Patented Feb. 24,1959

prising an upwardly extending hook or loop 80 receiving an adjacent portion of the thread 82.

In Figure 4 the loop 80 is shown receiving the unbroken tensioned thread 82 and in Figure the thread 82 has broken and the lop is disengaged therefrom.

A second horizontally disposed lever 84 is spaced from the first lever 74 and isrconnected at its intermediate portion to the plate 66 for movement upwardly and downwardly about asecond' axis transverse of the plate 66. The lever 84 is provided with a weight 86 (Figure 2) on one 'end thereof and has an upwardly extending arm 88 having notches 90 on the inner edge thereof.

Meansare provided connecting the second lever 84 to the first lever 74 formovement with the latter.

Specifically, thismean's embodies a link bar 92 having one end pivotally connected to-a weighted end of the lever 84 and having the other end pivotally connected to the end of the lever 74 remote from theloop 88.

The present invention provides a latch" element, designated generally'by the reference numeral 94 and shown most clearly inFigure 3, for fixed attachment to the latch lever 58. The attachment of the latch lever 58 to the latch lever support arm 52 is accomplished by. means of an elongated stud bolt 96 having a shoulder 98 and threadedly engaged in the latch lever support arm 52 with the latch lever 58 pivotally supported between the arm 52 and the shoulder 98.

The latch element 94 is attached to the latch lever 58 by unscrewing the stud bolt 96 and positioning the latch element 94 between the shoulder 98 on the bolt 96 and the adjacent face of the latch lever 58. A hole 102 is provided for receiving the stud bolt 96 and the lower end of the latch element 94-is arcuately curved so as to fit over the hub of the hinge screw 50.

In operation, the attachment according to the present invention maintains the cutter or knife 36 in the inoperative position during the'cycle of a buttonhole making operation when the tension on the thread 18 is released. This tension may be the result of either breaking of the thread 18 or breaking of the lower thread within the base of the sewing machine. Upon breakage of the lower thread, the upper thread is not locked within the fabric of the work piece and tension is thereby relieved in the thread 18. Upon release of tension in the thread 18, the lever 74 is caused to tilt in the counterclockwise direction, Figure 1, due to the action of the force of gravity upon theend portion 78 of the lever 74, together with the weight of the link bar 92 and the weight of the Weighted second lever 84. The counterclockwise movementofthe lever 74 efiects the clockwise movement of the=second lever'84 and raises the arm 88 to a position in which it engages the leg 100 of the latch element 94 to hold'thelatch lever 58 from movement to the position in: which the shoulder 60 renders inoperative the lost motion connection between the power operated lever 46 and the knife driving lever 42. Upon replacement of the broken thread 18 or the broken lower thread (not shown), the tension is again placed in the thread 18 and the engagement of the loop 80 with the portion of the thread 18 adjacent the tensioner 26 returns the levers 74 and 84 to their former horizontal position with the leg 100 of the latch element 94 out of engagement with the notches in the arm 88.

= The attachment according to the present invention has great sensitivity and instantly renders inoperative the cutter or knife 86 and restrains it from cutting the fabric of the workpiece if for any reason the stitches of the buttonholeare incomplete due to the breaking of either the thread 18 or the thread carried by the bobbin or other'mcchanism below the table of the stitching machine.

What is claimed is:

1. An attachment for operative connection with the frame ofa buttonhole stitching machine including a thread-carrying needle, a buttonhole cutter, a cutter operatmg'lever, a-power operated lever, a lost motion connection between said levers, and'a latch lever springurged into interlocking connection with the levers and normally retained in retractive inoperative position during a stitching cycle by a cam controlled member, said attachment comprising a supporting plate adapted to be fixedly attached to said frame, a first horizontally disposed lever connected adjacent its mid point to said plate for movement upwardly and downwardly about a first axis transverse of said plate, one end of said first lever being provided with sewing thread engageable means whereby the first lever is maintained in the horizontal position by the normal tension in the thread;- a second horizontally disposed lever spaced from said-first lever and connected at its intermediate portion to said plate for movement upwardly and downwardly about a second axis transverse of said plate,'latch means on one end ofsaid second lever, means connecting said second lever tosaid first lever for movement with the latter, and a latch element fixedly attached to said latch leverand normally out of engagement with said latch means and movable responsive to the release of the tension of the thread into engagement with said latch means for restraining said latch lever against movement into operative position for effecting a buttonhole cutting operation.

2. An attachment for operative connection with the frame of a buttonhole stitching machine including a thread-carrying needle, a buttonhole cutter, a cutter operating lever, a power operated lever, a lost motion connection between said levers, and a latch lever springurged into interlocking connection with the levers and normally retained in retractive inoperative position during a stitching cycle by a cam controlled member, said attachment comprising a supporting plate adapted to be fixedly attached to said frame, a first horizontally disposed lever connected adjacent its mid point to said plate for movement upwardly and downwardly about a first axis transverse of said plate, means carried by said plate engageable with said first lever for limiting the downward movement of the latter, one end of said first lever being provided with sewing thread engageable means whereby the first lever is maintained in the horizontal position by the normal tension in the thread, a second horizontally disposed lever spaced from said first lever and connected at its intermediate portion to said plate for movement upwardly and downwardly about a second axis transverse of said plate, latch means on one end of said second lever, means connecting said second lever to said first lever for movement with the latter, and a latch element fixedly attached to said latch lever and normally out of engagement with said latch means and movable'responsive to the release of the tension of the thread into engagement with said latch means for restraining said latch lever against movement into operative position for effecting a buttonhole cutting operation.

3. An attachment for operative connection with the frame of a buttonhole stitching machine including a thread-carrying needle, a buttonhole cutter, a cutter operating lever, a power operated lever, a lost motion connection between said levers, and a latch lever springurged into interlocking connection with the levers and normally retained in retractive inoperative position during a stitching cycle by a cam controlled member, said attachment comprising a supporting plate adapted to be fixedly attached to said frame, a first horizontally disposed lever connected adjacent its mid point to said plate for movement upwardly and downwardly about a first axis transverse of said plate, one end ofsaid first lever being provided with sewing thread engageablemeans whereby the first lever is maintained in the horizontal position by the normal tension in the thread, a second horizontally disposed lever spaced from said first lever and connected at its intermediate portion to said plate for movement upwardly and downwardly about a second axis transverse of said plate, latch means on one end of said second lever, means connecting'said second lever References Cited in the file of this patent into operative position for effecting a buttonhole cutting 10 2,681,024

operation.

UNITED STATES PATENTS Schaeffer May 7, 1912 Krell June 30, 1914 Miller Dec. 12, 1922 Miller Dec. 12, 1933 Leonard July 14, 1953 Deitch June 15, 1954 

